Copper-silicon-selenium alloys



Patented Apr. 21, 1936 UNITED STATES COPPER-SILICON-SELENIUM ALLOYS Cyril Stanley Smith, Cheshire, Conn., assignor to .The American Brass Company, Waterbury, Com, a corporation of Connecticut No Drawing. Original application September 2,

1933, Serial No. 687,967. Divided and this application October 11, 1934, Serial No. 747,931

8 Claims.

My invention relates to. a series of alloys of copper characterized by high strength and duetility and at the same time distinguished by a remarkable ease of The free-cutting qualities are achieved without great sacrifice of strength or ductility by making additions of selenium to alloys which consist substantially of copper and silicon, together, generally with small quantities of other elements.

10 This application is a division of my prior application Serial Number 68'7,-967, filed September 2, 1933 for Copper-selenium alloys.

One of the most useful groups of copper alloys at present finding industrial application are those based on the binary copper-silicon alloys containing, usually, not over 5 percent silicon, and generally with additions of other elements such, for example, as zinc, tin, and iron, which elements are added for the purpose of improving the casting have an adverse efiect on the hot or cold working properties.

I have studied the tensile properties and machining characteristics of alloys containing approximately 3.75 percent silicon with various ad- 5 ditions of selenium up to 1.0 percent in the form of hot rolled and drawn rods. The results of my tests are given in table I following from which it can be seen that the presence of selenium does not greatly reduce the ductility of the alloys and 10 is almost without efiect on the tensile strength. The machinability was measured by counting the number of turns necessary for a standard drill to form a standard hole under a. given load. The higher the number of turns necessary the less 15 machinable the alloy is. It can be readily appreciated from the figures in table I how advantageous the selenium additions are in improving machinability. Very small additions of selenium will improve the machinability and the efiect inand qualities of the alloys h creases with further additions although large corrosion resistance. On account of their lngh amounts cause the alloy to become somewhat strength a toughness the alloys have machmbrittle. The best compromise between ductility 111g quehtles about the Same as mild Steel, t I and machinabillty occurs at about 0.5 to 1.0 perhave found that additions of selenium to these t selenium, lth h for special purposes 11; 25 pp mm l y h a great effect n D m may prove advisable to use either larger or ing machinability and that selenium does not smaller amounts than this.

Tum: I Tensile properties and maohbtability of cold drawn and annealed copper-swoon alloys 30 i contammg selenium 1 00 tion 111; AnoyN-o. :mposi perm lgnt Tcfisilestrejfigth 31 Reduction? bllmlacliilini- 35 01115011 Selenium 100 3 01. Pmmt mpemn a w u 35 Cold lraum 0. 70 o. 0 55,000 111,850 10. 4 50. 0 020 0.00 0.12 55,750 110,250 10.4 54.5 104 000 0.25 54,700 112,100 15.0 42.1 100 40 0. 02 0. 51 52,000 110,000 10.0 20.0 as 40 Annealed 1 tour at 760 C. 0.70 0.0 20,400 01, 050 70.7 07.0 (102) 0.00 0.12 20,000 02,550 07.1 70.0 100 0.00 0.25 25, 550 02,050 04.7 00.0 114 0.02 0.51 20,250 01,500 50.0 47.0 05 45 Th se allo a were hot rolled f 0 3 i t 0.625 in., a1 11' 11 Id 11 t .5 i in two 0 passes. Gauge lellgth of test pieces0 .857 in?diameter. Mme e an co mm o o n Number or turns of 0.25 in. drill necessary to penetrate 0.25 in. under load of 86 pounds.

Selenium may be added to any complex copper-silicon alloys containing one or more of the elements listed above, or any other elements, with as much facility as to the binary alloys, unless there is present a large amount of some element which combines with selenium in preference to the copper and forms a selenide which common elements which do not prevent the retention of selenium in the alloys, I have found the following: iron, tin, antimony, silver, phosphorus, cadmium, silicon, and nickel. The elements magnesium and calcium, if present in sufllcient quantity, tend to eliminate the selenium, and zinc if present to the extent of more than about 15 percent has a similar effect. In the case of manganese, amounts up to 0.5 percent are permissible, although 1.0 percent causes segregation of what is presumably manganese-selenide. For all these elements which combine with selenium more avidly than does copper there will be a limiting concentration below which the insoluble selenide will not form and the selenium will remain distributed uniformly throughout the alloy, but above which concentration the selenide is insoluble in the liquid. The above remarks are based on experiments with alloys containing 1 percent selenium to which were added the various elements enumerated and it is probable that larger amounts of the elements could be tolerated without producing segregation if a smaller amount of selenium were present.

The range of selenium may be from 0.05 percent to 4.0 percent but is preferably from 0.05 percent to about 2 percent. The silicon may be in appreciable amount up to 5 percent.

Some of the complex alloys which in the present state of the art seem to have some promise are alloys containing 0.25 percent to 5 percent silicon, 0.05 to 2 percent selenium with additions of one or more of the following elements, the

balance being principally copper: 0 to 20 percent zinc, 0 to 30 percent nickel, 0 to 5 percent iron, 0 to 15 percent tin, 0 to' 2 percent cadmium: alloys containing 0.25 to 5 percent silicon, 0 to 11 percent iron, 0 to 10 percent zinc, 0.05 to 2 percent selenium, the balance being principally copper: an alloy containing approximately 3.5 percent silicon, 2.0 percent iron, 2.0 percent zinc, 1.0 percent selenium, the balance being principally copper: alloys containing 0.25 to 5 percent silicon, 0.05 to 2 percent selenium, 0 to 10 percent tin, balance principally copper: an alloy containing approximately 1.75 percent silicon, 1.0 percent tin, 1.0 percent selenium, the balance being principally copper: alloys containing 0.25 to 5 percent silicon, 0.05 to 2 percent selenium, 0 to 20 percent zinc, the balance being principally copper; an alloy containing 0.25 percent to 5 percent silicon, 0.05 to 2 percent selenium, and bal- .ahce principally copper; an -lloy containing approximately 4.0 percent silicon, approximately 1.0 percent selenium, and approximately percent copper; alloys containing .25 to 5 percent silicon, 0 to 10 percent zinc, 0 to 5 percent tin, 0.05 to 2.0 percent selenium, the balance being principally copper; and an alloy containing approximately 3.25 percent silicon, 1.5 percent zinc, 0.5 percent tin, 1.0 percent selenium, the balance being principally copper.

Selenium may be added to copper alloys either with the cold furnace charge or it may be added to the molten alloy in the form of the element or as copper-selenide, which is soluble in molten copper to the extent of 4 percent selenium, although the solubility is afieoted by the presence of other elements. On account of the volatility of selenium and the poisonous nature of its fumes the addition is preferably made as copper-selenide which is a stable compound of melting point above that of copper. Selenium exists in the solid alloys in the form of particles of, CuaSe evidently resulting from the solidification of the eutectic, and these particles in the alloys break up the chips formed by the cutting tool, and thus facilitate the cutting operation. When the alloys are worked, the particles elongate into long thin fibers but these become rounded again on annealing.

Although I have disclosed herein the addition of selenium to copper-silicon alloys and a few specific alloys, addition of selenium may be made to any alloys of copper with the disclosed or other elements, singly ,or combined in any manner, providing there is not an excessive amount of selenide formed that is insoluble in the liquid alloy and that is sufliciently different in density to be rapidly eliminated from the molten alloys. As examples of complex alloys I have made and used those containing copper with silicon, tin and selenium; copper with silicon, iron, zinc and selenium. It is obvious, however, that there is almost no limit to the alloys .of copper which can begmade and to which selenium is a helpful addition when free-cutting qualities are desired. My invention covers the addition of selenium either as the element, copper-selenide or any other form to relatively pure copper-silicon alsulphur and tellurium may be added in minor proportions to the copper-silicon-selenium alloys and produce a somewhat similar effect. Under certain conditions it may prove advisable to use additions of two or more of the elements simultaneously and it should be understood that whenever selenium is mentioned in this specification selenium with a smaller quantity of either of the elements sulphur or tellurium or sulphur and tellurium may be included.

Having thus set forth the nature of my invention, what I claim is:

1. A copper base alloy which is characterized by ease of machining and which is workable by hot or cold rolling, containing silicon 0.25 to 5.0 percent, selenium 0.05 to 2.0 percent.

2. A copper base alloy which is characterized by case of machining and which is workable by hot or cold rolling, containing silicon 4.0 percent, selenium 1.0 percent. v

3. A copper base alloy which is characterized by ease of and which is workable by hot or cold rolling containing silicon 4.0 percent, selenium 0.5 percent.

4. Copper alloys capable of being hot and cold worked and machined at high speeds containing 0.25 to 1% selenium, 0.25 to 5% silicon, balance copper.

5. An alloy containing silicon in appreciable amount and up to 5.0 percent, from 0.05 percent to 2.0 percent selenium and balance copper.

6. An alloy containing approximately 4.0

it is at once obvious that the percent silicon; 1.0 percent selenium, and 95.0-

percent copper.

7. A copper base alloy characterized by ductility and free cutting qualities containing silicon in appreciable amount and up to 5.0 percent, and from 0.05 percent to 4 percent selenium.

8. Copper alloys capable of being hot and cold worked and machined at high speeds containing 0.05 to 2 percent of selenium, 0.25 to 5 percent of silicon, balance copper.

CYRIL STANLEY SMITH. 

